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#500 by tchernik on 05 Jul, 2017 16:51
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...snip...
Where I am now.
Advanced designs incorporated into the drive required more than just the RF source to the frustum, those required a battery source that "rides" on the pendulum arm. This dramatically increased the load bearing requirements of the pendulum wire and the complexity of the build to the point that it became a Rube Goldberg nightmare and not realistic. Unlike monormorphic who is pursuing 1-25 watts in a pure RF drive I need more power. (Love that line
)
I'd recommend those who are building a device review what the industry recommends in evaluating micro-thrusters in several test beds to achieve credible results and not have to reinvent the wheel.
PDF warning...
http://hpepl.ae.gatech.edu/papers/2013_IEPC_Polk.pdf
Because I've seen more than just the small m/N thrust anomalies that need to be characterized I'm rebuilding the hanging wire torsion pendulum by using flexure bearings.
I have several sets left over from building semiconductor equipment that required extreme precision rotational capabilities.
...snip...
Shells,
Your setup certainly looks like the best in town. Ha, no, make that among the best worldwide.
But now I'm eager to know more about your results.
I understand you are following a better be cautious than sorry approach for this, probably checking and double checking your results yourself and with other qualified people's help. And the harsh comments some Emdrive builders have received, while being completely honest and open on the net, may have inclined you to be quite more cautious while disclosing similar information.
But my doubt now is: are you still planning to release your results in the net or do you plan to make a paper and have it peer reviewed?
That last option doesn't seem unreasonable at all, specially if you have reasonably good confirmation and because your setup may have already exceeded the quality and rigor of some of the known setups, used to get Emdrive ball rolling not long ago, like those of Yang Juan we know about.
Also, a paper would help anchor the Emdrive even more firmly into the academic world, made of results that can be cited/quoted.
Thanks for the update. -
#501 by Bob012345 on 05 Jul, 2017 17:32
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Why can't a ship in principle create a disposable, unattached local medium with huge index of refraction, say 1E8 and emit laser light or microwaves in it thus imparting a billion times the kick to the ship over a photon beam in free space. One has to create and release the medium but if it's a low density gas in the form of a Bose Einstein Condensate, it wouldn't be much material. Alternatively, we could seek some other method of changing the index of refraction of space using only energy.
If the differences of Minkowski's and Abrahams' momenta of light have anything to do with the Emdrive, the transparent medium (the probably ionized gas) inside of the cavity would be a significant part of the effect.
Which means an Emdrive on a near full vacuum tested here on Earth would be noticeably less efficient than one on an atmosphere, but probably not null, because in any "vacuum" we can make on Earth there are some traces of gas left and the cavity could sustain some out-gassing during its function.
But if we tested it in a near perfect and self-replenishing vacuum (like in deep space), there the thrust could perfectly go to zero or become negligible/undetectable. Unless we were smart and prepared some test article where the cavity is airtight and contains some inert gas.
Thanks. My question though wasn't directly in reference to an EmDrive. The problem would still be a contained medium in an EmDrive cavity would cancel out net forces. Shawyer's appeal to the cavity being an open system under relativity makes more sense to me. My question related to using the Minkowski momentum to boost light momentum directly but not assuming a closed system. I'm letting the medium disperse. -
#502 by Bob012345 on 05 Jul, 2017 18:24
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A problem with testing a microwave source that is disconnected from the cavity, such that it can exist in another frame is that light would travel between the two frames. This would likely cause mutual repulsion between the two frames similar to a Photonic laser thruster: https://en.wikipedia.org/wiki/Photonic_laser_thruster . These have already been shown to work. Disconnecting the frames may fundamentally change what it is.
Really? Photonic thrust - recalling from mind - gives you only 3.3 nanonewton/watt. Not something to worry about, isn't it?
Equivalent to using a medium to increase light momentum is using mirrors to bounce the beam as in Photonic Laser Thrusters which have been shown to work in the lab pushing Kg scale objects around with light. Since mirrors are inconvenient as a reaction mass we can explore the concept of creating nano or micro-mirrors which last a brief time yet reflect the beam millions of times or more in their lifetime. Assume each mirror contained only micrograms of material and was created something like a high tech soap bubble in a plane mere microns away from the beam, also forming a plane to distribute the energy. Since light travels at 3E5 microns per nanosecond, we might get many bounces from each mirror even assuming the mirrors recede at great acceleration. Perhaps thousand of bounces per nanosecond and millions per microsecond if the mirrors last that long. Well, not exactly a Warp Bubble drive but perhaps more like Soap Bubble drive....
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#503 by Peter Lauwer on 05 Jul, 2017 18:41
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A problem with testing a microwave source that is disconnected from the cavity, such that it can exist in another frame is that light would travel between the two frames. This would likely cause mutual repulsion between the two frames similar to a Photonic laser thruster: https://en.wikipedia.org/wiki/Photonic_laser_thruster . These have already been shown to work. Disconnecting the frames may fundamentally change what it is.
Really? Photonic thrust - recalling from mind - gives you only 3.3 nanonewton/watt. Not something to worry about, isn't it?
Equivalent to using a medium to increase light momentum is using mirrors to bounce the beam as in Photonic Laser Thrusters which have been shown to work in the lab pushing Kg scale objects around with light. Since mirrors are inconvenient as a reaction mass we can explore the concept of creating nano or micro-mirrors which last a brief time yet reflect the beam millions of times or more in their lifetime. Assume each mirror contained only micrograms of material and was created something like a high tech soap bubble in a plane mere microns away from the beam, also forming a plane to distribute the energy. Since light travels at 3E5 microns per nanosecond, we might get many bounces from each mirror even assuming the mirrors recede at great acceleration. Perhaps thousand of bounces per nanosecond and millions per microsecond if the mirrors last that long. Well, not exactly a Warp Bubble drive but perhaps more like Soap Bubble drive....
These 'microsized mirrors' you mention will not work. The 'absorb' the momentum. I think the whole point is that you reflect on one side from an 'infinite mass' (moon or earth). But I have not read the article. -
#504 by SeeShells on 05 Jul, 2017 19:02
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I agree with most of your assessment although if I may add a few thoughts on what I did and why, to provide a high power stable 2.45GHz narrow band frequency to the frustum.Again, thanks a lot for the sims. But the frequencies you got out of it, 3.50 and 3.35 GHz, do not really come close to the measured frequencies (3.60 and 3.25 GHz).
Does it due to, apart from the influence of the connectors etc., the fact that one of the endplates in not in contact with the wall?
Peter
Added: I guess it is best to paint the cavity and take pictures with an IR camera to determine what modes it is running.
I think the difference is likely both, but more because of the connectors and coax inside the cavity. It is a fairly small cavity with a lot of clutter inside. Unless I modeled the exact fittings and curve of the coax, there is likely to be quite a difference between the sim and measured resonance.
My workaround to this problem was to fabricate the simplest antenna that could excite the TE modes and mount it close to the end-plate so only a very small portion of the connector extended into the cavity. This yielded measurements that were very close to the simulations.
For the 'EMDrive frustum' that is a very good solution. But for the 'coupling cavity' it is too narrow bandwidth. In order to be usable, the coupling cavity needs to be rather broadband (at least a few MHz) since trough it, you have to feed the frustum (with a shifting resonance frequency due to temp change).
As most here know I did my own clean variable DC power supplies driving a thermally stabilized copper lined water jacket magnetron with an radiator heat exchanger. This drives a magnetron>antenna> cavity much like the one you did, but with a tuning endplate captured with a quartz rod through the center that allows thermal expansion in the resonate cavity. It maintains the frequency and keeps the mode locked. The magnetron has the ability to "lock" to the resonate frequency of the waveguide when driving this arrangement. This gave me a stable RF source that was stable, variable in power and some flexibility in frequency tuning.
I use the output of this waveguide to drive into a frustum that utilizes the same thermally stabilized design. A Quartz tuning rod for stabilizing the thermal expansion and contraction as the Drive cavity fills with RF. *attached image
My Very Best,
Shell
opps... 2.45GHz
A thought from somebody who has built high power microwave systems for CVD.
I noticed in the figures your sliding plate with flexible beryllium gasket at its periphery. If this is a finger stock type of seal, and if it is at a point where skin currents are large, local high temperatures can oxidize the finger stock elements. Then high resistance, higher temperatures, then local finger melting. Also, copper is inherently "sticky" and tends to score or gall with finger stock motion.
To eliminate these effects in moving finger stock seals engaged with both copper and aluminum walls and in stub tuners, I used a thin layer of silver paste spread over the expected range of motion. Silver is electrically conductive and inherently lubricious. It eliminated scoring, galling, and the other rubbing phenomena that caused my finger stock seals and tuning stubs to fail.
Eventually, I silver-plated every surface that carried skin currents. Problem solved. But the paste was an effective interim solution.
If your flexible beryllium seal is a non-finger stock design, what I've written may be irrelevant, please ignore.
Hi MikeGem,
Great thoughts and post, I'll not ignore them.
When I did the beryllium gasket I was chasing a TM mode, in which currents travel between the sidewalls and endplates and I needed to make sure that the fields created by the current flows were uniform. Am I correct in your microwave cavities for CVD you use TMxxx modes?
I switched to the cavity operating in a TE013 mode which doesn't carry endplate>sidewall currents although I needed a tight fit between the two and redid the copper endplate to the ceramic plate where it was a snug fit. *See pic. I still soldered copper braided ground straps between the endplate and sidewall of the tuning chamber.
I've used the silver pastes before making sure the large endplate was sealed well to the sidewalls.
My Very Best!
Shell
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#505 by Bob012345 on 05 Jul, 2017 19:29
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A problem with testing a microwave source that is disconnected from the cavity, such that it can exist in another frame is that light would travel between the two frames. This would likely cause mutual repulsion between the two frames similar to a Photonic laser thruster: https://en.wikipedia.org/wiki/Photonic_laser_thruster . These have already been shown to work. Disconnecting the frames may fundamentally change what it is.
Really? Photonic thrust - recalling from mind - gives you only 3.3 nanonewton/watt. Not something to worry about, isn't it?
Equivalent to using a medium to increase light momentum is using mirrors to bounce the beam as in Photonic Laser Thrusters which have been shown to work in the lab pushing Kg scale objects around with light. Since mirrors are inconvenient as a reaction mass we can explore the concept of creating nano or micro-mirrors which last a brief time yet reflect the beam millions of times or more in their lifetime. Assume each mirror contained only micrograms of material and was created something like a high tech soap bubble in a plane mere microns away from the beam, also forming a plane to distribute the energy. Since light travels at 3E5 microns per nanosecond, we might get many bounces from each mirror even assuming the mirrors recede at great acceleration. Perhaps thousand of bounces per nanosecond and millions per microsecond if the mirrors last that long. Well, not exactly a Warp Bubble drive but perhaps more like Soap Bubble drive....
These 'microsized mirrors' you mention will not work. The 'absorb' the momentum. I think the whole point is that you reflect on one side from an 'infinite mass' (moon or earth). But I have not read the article.
Thanks. Solar sails rely on reflecting the light beam for maximum momentum. The beam delivers very little energy to the sail until they become highly relativistic. I'd have to see numbers to believe they can't reflect a lot of light, enough to greatly enhance the light's action on the ship. Certainly, the light get downshifted as the mirror velocity gets relativistic but I think the useful period is well below that point. I see no reason yet that useful light can't be recirculated by these ultra thin mirrors up to a point. -
#506 by SeeShells on 05 Jul, 2017 19:37
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Thanks for the complements, although I don't believe I have the best setup in the world....snip...
Where I am now.
Advanced designs incorporated into the drive required more than just the RF source to the frustum, those required a battery source that "rides" on the pendulum arm. This dramatically increased the load bearing requirements of the pendulum wire and the complexity of the build to the point that it became a Rube Goldberg nightmare and not realistic. Unlike monormorphic who is pursuing 1-25 watts in a pure RF drive I need more power. (Love that line)
I'd recommend those who are building a device review what the industry recommends in evaluating micro-thrusters in several test beds to achieve credible results and not have to reinvent the wheel.
PDF warning...
http://hpepl.ae.gatech.edu/papers/2013_IEPC_Polk.pdf
Because I've seen more than just the small m/N thrust anomalies that need to be characterized I'm rebuilding the hanging wire torsion pendulum by using flexure bearings.
I have several sets left over from building semiconductor equipment that required extreme precision rotational capabilities.
...snip...
Shells,
Your setup certainly looks like the best in town. Ha, no, make that among the best worldwide.
But now I'm eager to know more about your results.
I understand you are following a better be cautious than sorry approach for this, probably checking and double checking your results yourself and with other qualified people's help. And the harsh comments some Emdrive builders have received, while being completely honest and open on the net, may have inclined you to be quite more cautious while disclosing similar information.
But my doubt now is: are you still planning to release your results in the net or do you plan to make a paper and have it peer reviewed?
That last option doesn't seem unreasonable at all, specially if you have reasonably good confirmation and because your setup may have already exceeded the quality and rigor of some of the known setups, used to get Emdrive ball rolling not long ago, like those of Yang Juan we know about.
Also, a paper would help anchor the Emdrive even more firmly into the academic world, made of results that can be cited/quoted.
Thanks for the update.
I believe no matter the rigors undertaken and the attention to detail it still will be criticized and critiqued to the extreme just like any others who have published results.
As to how and when and with who (other collaborators) I publish I'm going to keep it close to the vest as we say. Assured I will release my final results to the public. Also know there is a lot of work still to be done.
My Very Best,
Shell -
#507 by PotomacNeuron on 05 Jul, 2017 21:30
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Hi MikeGem,
Great thoughts and post, I'll not ignore them.
When I did the beryllium gasket I was chasing a TM mode, in which currents travel between the sidewalls and endplates and I needed to make sure that the fields created by the current flows were uniform. Am I correct in your microwave cavities for CVD you use TMxxx modes?
I switched to the cavity operating in a TE013 mode which doesn't carry endplate>sidewall currents although I needed a tight fit between the two and redid the copper endplate to the ceramic plate where it was a snug fit. *See pic. I still soldered copper braided ground straps between the endplate and sidewall of the tuning chamber.
I've used the silver pastes before making sure the large endplate was sealed well to the sidewalls.
My Very Best!
Shell
Beryllium is toxic. Silver idea may have its merit on this regard. -
#508 by PotomacNeuron on 05 Jul, 2017 21:38
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Thanks for the complements, I try.
I tried both, waveguides to the frustum and stress relieved high flex coax cabling with the Torsion Pendulum design.
I used a larger air gap non-contact waveguide freely rotating center much like what you did and a more compact design (which proved too demanding in machining with my current tools). I plan to revisit the tiny design when I get my lathe.
Both designs tended to leak some at the air gap which I don't like and had to put a small local floating Faraday cage around them. On another note the power levels in both designs would vary to the frustum during rotations of the drive on the wire pendulum. This was due the free hanging arm on the wire and imperfections in the cavity build, antenna etc made the torsion arm flex around and the floating top plate could hit the sides.
Where I am now.
Advanced designs incorporated into the drive required more than just the RF source to the frustum, those required a battery source that "rides" on the pendulum arm. This dramatically increased the load bearing requirements of the pendulum wire and the complexity of the build to the point that it became a Rube Goldberg nightmare and not realistic. Unlike monormorphic who is pursuing 1-25 watts in a pure RF drive I need more power. (Love that line)
I'd recommend those who are building a device review what the industry recommends in evaluating micro-thrusters in several test beds to achieve credible results and not have to reinvent the wheel.
PDF warning...
http://hpepl.ae.gatech.edu/papers/2013_IEPC_Polk.pdf
Because I've seen more than just the small m/N thrust anomalies that need to be characterized I'm rebuilding the hanging wire torsion pendulum by using flexure bearings.
I have several sets left over from building semiconductor equipment that required extreme precision rotational capabilities.
When I was building a 4 axis machine a couple years ago.
By luck I still had a few of the parts left over. I'm using them to build the flexure torsional pendulum with some mods.
This will allow measurements into the µN- to mN-level thrust and uto N-level impulses and provide support to the higher power requirements I need.
Also I could use Galinstan, a Gallium/Indium/Tin contacts for sensors and still use the high power non-contact microwave waveguide. But I believe I have a better fix to get away from the Galinstan issues and using it altogether.
This isn't a air bearing rotational stand (which has issues and is costly) or a Torsional Wire Pendulum (which reached limits in the design). The Flexure bearing design follows many of the industry guidelines for thruster testing and gives me the wide range of measurements I need.
My Very Best,
Shell
This kind of bearing has its own problems. The weight of the experiment platform will droop the part of the bearing that is fixed to the platform. Even if the other part of the bearing is installed perfectly vertical, the movement of the platform will not be in the horizontal plane. Thus any mass center shift will induce force that is hard to separate from thrust. EW's 2015 experiment potentially had this problem that was not addressed in their paper (the peer reviewed one). EW's 2014 experiment is affected less by this problem because the response was "fast". -
#509 by SeeShells on 05 Jul, 2017 21:41
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Hi MikeGem,
Great thoughts and post, I'll not ignore them.
When I did the beryllium gasket I was chasing a TM mode, in which currents travel between the sidewalls and endplates and I needed to make sure that the fields created by the current flows were uniform. Am I correct in your microwave cavities for CVD you use TMxxx modes?
I switched to the cavity operating in a TE013 mode which doesn't carry endplate>sidewall currents although I needed a tight fit between the two and redid the copper endplate to the ceramic plate where it was a snug fit. *See pic. I still soldered copper braided ground straps between the endplate and sidewall of the tuning chamber.
I've used the silver pastes before making sure the large endplate was sealed well to the sidewalls.
My Very Best!
Shell
Beryllium is toxic. Silver idea may have its merit on this regard.
It is in some forms.
https://en.wikipedia.org/wiki/Beryllium_poisoningQuoteBeryllium poisoning is poisoning by the toxic effects of beryllium, or more usually its compounds. It takes two forms:
Acute beryllium poisoning, usually as a result of exposure to soluble beryllium salts
Chronic beryllium disease (CBD) or berylliosis, usually as a result of long-term exposure to beryllium oxide usually caused by inhalation.
https://en.wikipedia.org/wiki/Beryllium_copper#ToxicityQuoteIn solid form and as finished objects, beryllium copper presents no known health hazard.
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#510 by Monomorphic on 05 Jul, 2017 22:06
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The Flexure bearing design follows many of the industry guidelines for thruster testing and gives me the wide range of measurements I need.
I agree this is the next logical step after the hanging wire pendulum. Adding flexure bearings has been pretty high on my list since I reached the ~3uN noise floor with my current build.
EW used something called Riverhawk Company, Core Flex; Square Mount: http://flexpivots.com/linear-flexure-bearing/
Heidi Fearn uses a C-Flex bearing. E-10: https://c-flex.com/
The C-Flex E-10 has a max load of 22.8 lbs. Since they are used in pairs, I think that doubles to ~45lbs.
An emdrive experiment with batteries, frustum, amplifier, extruded aluminum, and more, may be too much for the E-10. Might be better to go with the F-10 for 33.6lbs for a total of ~67lbs.
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#511 by SeeShells on 05 Jul, 2017 22:28
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I started using C-Flex bearings almost 14 years ago in my business. I have the F-10 bearings.The Flexure bearing design follows many of the industry guidelines for thruster testing and gives me the wide range of measurements I need.
I agree this is the next logical step after the hanging wire pendulum. Adding flexure bearings has been pretty high on my list since I reached the ~3uN noise floor with my current build.
EW used something called Riverhawk Company, Core Flex; Square Mount: http://flexpivots.com/linear-flexure-bearing/
Heidi Fearn uses a C-Flex bearing. E-10: https://c-flex.com/
The C-Flex E-10 has a max load of 22.8 lbs. Since they are used in pairs, I think that doubles to ~45lbs.
An emdrive experiment with batteries, frustum, amplifier, extruded aluminum, and more, may be too much for the E-10. Might be better to go with the F-10 for 33.6lbs for a total of ~67lbs.
Features
Frictionless
Backlash Free
Self Centering
Repeatability
Simple Installation
Low Hysteresis
Vacuum Applications
Stock Items
No Lubrication
No Maintenance
Indefinite Life -
#512 by Monomorphic on 05 Jul, 2017 23:08
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I started using C-Flex bearings almost 14 years ago in my business. I have the F-10 bearings.
A beefier battery-powered version of the "USC/ARC Fullerton Thrust Balance" is achievable for DIY emdrive experiments. I'm getting a price on those F-10 bearings. Do you recall their cost?
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#513 by SeeShells on 05 Jul, 2017 23:50
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Sorry monomorphic I do not recall the price we paid 10 years ago.I started using C-Flex bearings almost 14 years ago in my business. I have the F-10 bearings.
A beefier battery-powered version of the "USC/ARC Fullerton Thrust Balance" is achievable for DIY emdrive experiments. I'm getting a price on those F-10 bearings. Do you recall their cost?
Shell -
#514 by Monomorphic on 06 Jul, 2017 00:18
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Sorry monomorphic I do not recall the price we paid 10 years ago.
Shell
The equivalent Riverhawk flexure bearings are $106 each:
http://flexpivots.com/Single-Ended%20Cantilever%20Pivot%20Bearing%20Order%20Form/
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#515 by Augmentor on 06 Jul, 2017 05:03
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Quote from: Monomorphic on 07/05/2017 11:08 PM
Quote from: SeeShells on 07/05/2017 10:28 PM
I started using C-Flex bearings almost 14 years ago in my business. I have the F-10 bearings.
A beefier battery-powered version of the "USC/ARC Fullerton Thrust Balance" is achievable for DIY emdrive experiments. I'm getting a price on those F-10 bearings. Do you recall their cost?
FYI Woodward at CSU Fullerton uses E-10 bearings.
David M -
#516 by Anthony M on 06 Jul, 2017 06:09
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Hi. First and foremost I'm not a scientist, but more of an enthusiast. I took a much different career approach then most of you probably did and ended up serving in the Canadian Forces for over a decade specializing in radio communications.
I've done a lot of reading on the EM Drive and am wondering if anyone has tried to input a harmonic frequency on top of the regular frequency that you're testing with. Would this not amplify the signal without having to introduce more power?
I could be completely off here, just a thought I had.
Thanks in advance. -
#517 by demofsky on 06 Jul, 2017 07:41
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Hi. First and foremost I'm not a scientist, but more of an enthusiast. I took a much different career approach then most of you probably did and ended up serving in the Canadian Forces for over a decade specializing in radio communications.
This has been most recently discussed earlier in this tread (or later in the last thread). As part of the discussion a patent was posted where two frequencies were superimposed within a dielectric or magnetic medium - not a cavity!
I've done a lot of reading on the EM Drive and am wondering if anyone has tried to input a harmonic frequency on top of the regular frequency that you're testing with. Would this not amplify the signal without having to introduce more power?
I could be completely off here, just a thought I had.
Thanks in advance.
Another interesting angle on this is the possibility of improving performance by shaping the signal to what it would be like during movement. This would be conceptually like forward error correction where a signal is predistorted to travel through a medium more accurately.
All of this was difficult with magnetrons but now folks are moving to solid state and programable signal generators so once we get some fustrums with basic characterization done then these approaches can be examined to see if there is anything to them. -
#518 by Mark7777777 on 06 Jul, 2017 10:07
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#519 by Monomorphic on 06 Jul, 2017 12:59
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Message from C-Flex on pricing for the E-10 and F-10 flexure bearings:
P/N: E-10 Qty: 1- 15 pcs. at $57.19each
P/N: F-10 Qty: 1- 15 pcs. at $61.28each
Both are currently stock.
These prices are a lot better than Riverhawk.
Some kind of central mount will be needed. I found this image in one of Heidi's papers.
)
